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  • D-PILE GROUP

    3D modelling of single piles and pile groups

  • In 1988, Deltares (formerly known as GeoDel )

    started a research project on the behaviour of

    mooring dolphins. Deltares was asked to do so by

    the Dutch Ministry of Public Works. Within the

    project, it was shown that many di erent methods

    exist to perform calculations on single horizontally

    loaded piles and pile groups. Each method has

    its own advantages, but also limitations. None of

    the individual methods met all the criteria of the

    Dutch Ministry of Public Works. Therefore, Deltares

    decided to build a computer program that would

    hold several of these calculation models. The great

    advantage would be that the user could switch from

    one model to another, using the same input when

    applicable. One of the extra criteria for this program

    was that calculation times should still allow for

    practical use. The resulting program D-PILE GROUP

    has proved to be very useful. Previous releases of

    D-PILE GROUP were called MPile. For the modelling

    of pile groups two issues are important. First of

    all the behaviour of individual pile(s) in their own

    ground profi le is taken into account. Secondly one

    has to account for the behaviour (interaction) that

    each pile imposes on all other piles through the

    soil and through a superstructure. These issues are

    addressed in D-PILE GROUP using di erent models

    that range from a standard model to more complex

    models.

    General

    D-PILE GROUP enables the analysis of the three-dimensional

    behaviour of single piles and pile groups, interacting via the pile

    cap and the soil, as a function of loading. For this purpose D-PILE

    GROUP o ers a unique combination of the internationally accepted

    design rules of the API (American Petroleum Institute) and special

    soil interaction models all within the same graphical user interface.

    One of the great benefi ts of D-PILE GROUP is that switching between

    di erent computational models is very easy since all relevant input

    data of the previous model is kept. This fl exibility gives the user the

    opportunity to choose between a fast and simple calculation and

    a more complex but more accurate calculation, in a way that best

    suits particular needs. The choice of models to be used depends

    principally on the distance between piles. Some specifi c features

    of D-PILE GROUP are:

    Piles

    Analysis of all pile types, both pre-defi ned standard or

    userdefi ned special piles.

    Pile sections with di erent properties.

    Options for inclined piles (Cap; Cap Soil Interaction module and

    Dynamic module).

    Pile head fi xed or hinged clamp in the pile cap (freely rotating).

    Soil resistance

    Automated spring generation according to the API for sand

    and clay layers, for static or cyclic loading, with common input

    properties.

    Infl uence of the pile tip resistance (elastic or elasto-plastic).

    Loading

    Load on the cap by moments, horizontal and vertical forces,

    rotations and displacements.

    Load by horizontal and vertical soil displacements (Cap module).

    E ect of surcharge (Cap interaction module).

    Monotonous increasing loads, load reversal and repeated (cyclic)

    loads.

    Dynamic load by ship collision (Dynamic module), a model for

    undrained behaviour of sand.

    Multiple models for the interaction between piles via the soil.

    Output facilities

    Graphical output of displacements, shear forces and moments

    in top view.

    Graphs of cap displacements and rotations versus loading.

    Graphs of internal forces and soil reactions along the piles.

    Automatic generation of a calculation report with tables and

    graphs in rich text format. Exporting plotted data (e.g. to Excel).

    D-PILE GROUP3D modelling of single piles and pile groups

  • Pile properties window

    D-PILE GROUP comes as a standard module, which can be extended

    further with other modules to fi t more advanced applications:

    D-PILE GROUP Standard module (Poulos model)

    Cap module (included in Standard module)

    Plasti-Poulos module

    Cap Soil Interaction module

    Cap Layered Soil Interaction module

    Dynamic module.

    Standard module (Poulos module)

    The standard module is intended for the analyses of single piles

    and/or pile groups, using the Poulos module or the Cap module. The

    Graphic User Interface allows for the input of projects, running the

    analyses and provides tabular and graphical output of results both

    on screen and in a report. The program provides ample options for

    recalculation, using di erent pile types and fi ne-tuning of the pile

    plan. In this manner a cost e cient design can easily be obtained.

    Some specifi c features of the standard module will be described in

    the following paragraphs:

    Pile grid generator

    The pile grid generator eases the input of complex pile plans for

    equally spaced as well as non structured pile groups. A er the input

    of piles it is possible to check each pile graphically.

    Loads and soil displacement

    Loads and moments can be applied on the superstructure in all

    directions (x, y and z). As an alternative to force and moment

    controlled loading any of the loads can be replaced by its

    corresponding displacement or rotation. It is thus also possible to

    apply a prescribed translation or rotation in some or all directions

    (x, y and z). In the Cap module the piles can also be loaded directly

    by soil displacements.

    Output

    Input and output tables, graphs and a report are available for

    printing, viewing and for export to standard Windows applications

    through the Windows clipboard. Charts are available to show

    displacements, bending moments, shear forces, in x, y and z

    direction for individual piles. It is also possible to view results for

    Raking piles in High Speed rail viaduct

    Pile grid generator

  • Pile properties window

    displacements, bending moments and shear forces in a top view for

    all piles. Cap displacements and rotations can also be visualised.

    Poulos model

    The Poulos model is an analytical model that takes into account

    elastic soil behaviour for two soil layers. One layer along the

    pile and one layer located below the pile tip. Cap interaction and

    interaction between piles is taken into account. The Poulos model

    is especially useful in a fi rst analysis, when only little data is

    available or when the loads are small and the soil is expected to

    behave mainly elastically.

    Features

    Elastic soil behaviour.

    2 layers.

    Pile-soil-pile interaction for 2 layers.

    Cap module

    The Cap module is included in the standard module of D-PILE GROUP.

    The Cap module includes multilayered soils using linear or non linear

    (elasto-plastic) springs. Cap interaction is taken into account, but

    interactions between piles through soil are not taken into account.

    The Cap module is therefore especially useful for single pile

    analyses or pile groups with relatively large spacing. Generation

    of the springs requires limited input and o ers choices ranging

    from automatically created elasto-plastic springs according to

    the API rules to fully user defi ned spring characteristics (linear or

    elastoplastic).

    Features

    Elasto-plastic soil behaviour.

    Layered soil (max. 99 layers).

    No pile-soil-pile interaction.

    Input of prescribed displacements.

    Raking piles.

    Plasti-Poulos module

    As an extension of the Poulos model the Plasti-Poulos model

    includes non linear single pile behaviour based on the analysis of a

    pile in multilayered non linear soil. The behaviour of the half space

    is similar to the Poulos model (elastic). The Plasti-Poulos model

    can therefore be used for more accurate analyses compared to the

    Poulos model, in particular when larger loads are imposed and the

    system starts to show non linear e ects.

    Features

    Elasto-plastic soil behaviour.

    Layered soil (max. 99 layers).

    Pile-soil-pile interaction for 2 layers.

    Poulos model

    Cap model

    Plasti-Poulos model

    Output window for individual piles

  • Cap Soil Interaction module

    The Cap Soil Interaction module includes single pile behaviour

    based on the behaviour of multilayered non linear soils by means

    of lateral and axial (elastic/elasto-plastic) springs. It allows

    for input of non uniform piles while elastic soil-pile-soil group

    interaction is taken into account. This module is advised for small

    group spacings. It is not as fast as the above mentioned models,

    but provides detailed data about forces and moments along the

    length of the piles. It also allows for the use of surface loads.

    Features

    Elasto-plastic soil behaviour.

    Layered soil (max. 99 layers).

    Pile-soil-pile interaction for 1 layer.

    Surface loads.

    Raking piles.

    Cap Layered Soil Interaction module

    The Cap Layered Soil Interaction module is our most sophisticated

    model and includes single pile behaviour based on the behaviour

    of multilayered non linear soil modelled in continuum fi nite

    elements. It allows for input of non uniform piles wh